This gorgeous mayfly was photographed by an acquaintance on April 29, 2012, near the Touchet River in SE Washington. Let's see if you identify it, either by common name, or by family, or by genus, or by lifestage (dun or spinner), or by sex (male or female). Guesses are okay. Each will receive a prompt and respectful response. If this mayfly proves difficult to identify, additional clues will be provided.

Whats the difference between a Male and a Female. Don't they both look a like.

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Hi Old Man-

Good question. Most mayfly nymphs cannot easily be identified to sex from a photo. However, mayfly subimagos (duns) and imagos (spinners) can usually be identified to sex from a decent macro photo.

The most obvious clues are the size of the eyes, and the presence of claspers. The males usually have much larger eyes that the females, and males have claspers at the end of their abdomen (which look like calipers). Also (although this doesn't apply to duns), male spinners usually have extremely long fore (front) legs, as compared to the respective female spinners.

Speaking of which, what would be recommendations for a couple of (very good/very best) books for the NW?--Oregon and WA specifically, but ID, MT, CO, etc. wouldn't hurt. And yes, I'll need pictures in those books.

FlyFishingEntomology.com

Helping to fill a gap here on WFF with Entomology will be Roger Rohrbeck (Taxon). Roger has an impressive piece of work with FlyfishingEntomology.com and has consistently been the source of answers on the subject here on WFF. Rather than overlap efforts on the subject we'll have this forum area dedicated to subject with Roger moderating. Note the links below to his site. Thanks.